Re: [Discuss-gnuradio] PNG's of a neutral hydrogen observation at PARI with a USRP.

[Marcus Leech]

What's the bandwidth of the 10.7Mhz output of the R8500?

Was this a drift-scan, or were you tracking?

Fellow radio astronomers want to know :-)

I have an USRP on the way from Matt along, with a pre-release DBSRX.  It 
will be interesting
 to compare my spectral observations with yours, in the fullness of time.

Lamar Owen wrote:

> Attached are a couple of PNG's made at PARI with one of our two 26 meter 
> parabolics, 60dB of gain/downconversion from 1420MHz to 70MHz, and connected 
> to the 10.7MHz IF output of an ICOM R8500 tuned to 70MHz.  I set 
> average_alpha to the ridiculous value of 0.005 to get the smoothness.  Just 
> wish I could get a flat passband and 0.1dB per division. :-)  The 0.1dB per 
> division won't be too difficult, but the flat passband I understand will have 
> to wait.
>
> The version of usrp_fft.py I used I renamed spectro, and set the frequency 
> scale appropriately, as you will see in the images.
>
> Images are named with date and UTC time, telescope was at zenith and 
> collecting data close to the galactic plane.
>
> I do have a question:  I tried to set the fft size to 4096, and got an error 
> when I did that.  I need fft's with 65536 or more points, doable?
>
> Progress!
>  
>
>
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